As an optical information reader, bar code readers which read optical information of bar codes, two-dimensional codes, and the like indicating information such as names and prices of products are used widely by the distribution industry and the retail industry.
The bar code readers are roughly classified into hand-held ones held by one hand when in use and stationary ones, and the hand-held ones further include a pen type, a touch type, and a light beam scanning type (laser type). Among these, an optical information reader being an object of the invention. is an optical information reader such as a hand-held bar code reader of the light beam scanning type.
A bar code reader of the light beam scanning type shapes light emitted by a light source such as a laser diode (semiconductor laser) into a beam, deflects the light beam by a mirror so that the light beam hits on a bar code, and while rotating or vibrating (swinging) the mirror, scans the bar code so that the light beam moves across the bar code.
Then, the reflected light from the bar code is condensed, is received by a light-receiving sensor, and is converted to an electrical signal. The electrical signal is coded after A/D conversion and the resultant is output as bar code read information. In the hand-held optical information reader of the light beam scanning type, its read engine part is required to be greatly reduced in size and weight.
Under such circumstances, there has come into use a module for an optical information reader in which the aforesaid light source, a collimator lens for shaping the light emitted by the light source into a beam, a vibration mirror and it's driver, a collector mirror or a condenser lens, a light-receiving sensor, a processing circuit for a detection signal of the light-receiving sensor, and so on are assembled in a common easing to be modularized, as described in, for example, PLT 1, 2, 3, and so on.
In such a module for an optical information reader, a light-emitting unit whose light source is, for example, a laser diode, the collimator lens for turning the light emitted by the light source into a parallel luminous flux, and a member having an aperture through which the parallel luminous flux exits as a thin beam need to be fixedly positioned in a lens barrel, with their optical axes aligned. Further, in order for the collimator lens to surely generate the light beam which is to be converged in the parallel light flux or at a finite distance, it is necessary to accurately adjust the distance between the light-emitting unit and the collimator lens (collimation adjustment or focus adjustment) so that a focal point of the collimator lens and a light-emitting point of the light-emitting unit have a predetermined positional relation.
Therefore, in a light beam generating part in the module for the optical information reader disclosed in the aforesaid PLT 1, 2, 3, in part of the module casing, a lens-barrel hole is provided, at whose leading end portion the aperture being an aperture limit stop for letting the light beam exit therethrough is formed and whose rear end portion is opened to be formed as a press-fitting portion where to press-fit the light-emitting unit. Then, the collimator lens is bonded and fixed at a position short of the aperture, at a leading end rear side portion of the lens-barrel hole, and the light-emitting unit is pressed into the press-fitting portion from the rear end portion, whereby they are positioned.